The auxiliary power unit (APU) is a gas turbine engine that supplies electrical and pneumatic power to the aircraft systems as an auxiliary or secondary source of power. The APU allows the aircraft to be autonomous of external electric and pneumatic power sources on ground and in-flight.
The gearbox of the APU transfers power from the engine to electric power generators. These generators supply electric power to the power distribution center of the aircraft. The APU turbomachinery is mounted in a dedicated fire compartment in the tail cone of the aircraft, the APU compartment, while the power distribution center is traditionally installed in the nose section.
To meet the aircraft power needs, in some of the current designs, the APU turbomachine drives two electric power generators. These two generators operate as two independent power sources, so that the control and distribution of these conventional electric power distribution systems is fully duplicated. Thus, current electric power distribution systems include two sets of power feeder wires for connecting each generator with the power distribution center, and two generator control units, one generator control unit for each electric power generator.
As shown in FIG. 1, a conventional electric power distribution system includes an engine gearbox (2), a power distribution center (6), two or more three-phase electrical power generators (3) for being driven by the engine gearbox (2), and one generator control unit (7) for each generator (3). The electrical power generators (3) provide power to the power distribution center (6). Each generator control unit (7) is connected to each one of the generators (3) for calculating and providing the excitation current required for the generator (3) to reach a desired generated voltage. This way, conventional architectures maintain the system in a balance condition, where each electric power generator supplies same voltage to the power distribution center.
However, these conventional systems provide duplicated elements, such as generator control units and sets of power feeder wires, which entail a more complicated electric power distribution architecture, and at the same time that increase the cost and weight of the system.
Therefore, it would be desirable to provide an improved electric power distribution system that simplify conventional electric power distribution systems, and at the same time that reduce the associated weight while maximizing commonality and allow for reuse of components from the electrical architecture on existing aircrafts. Also, it would be desirable to reduce the cost associated to traditional electric power distribution systems.
Additionally, it would be desirable to extend these technical means to all aircraft engines, such as the main engines or the APU.